Wednesday, January 19, 2011

CBCT as a Tool in Endodontic Diagnosis

Cone Beam Computed Tomography (CBCT) is a valuable tool in endodontic diagnosis. The following case illustrates how CBCT provides added diagnostic information not available through traditional 2D imaging.

This patient was referred to our office today after a long week of infection and diagnostic dilemmas. Here's the story...

10 days ago with an ear ache.9 days ago pt reports pain to chewing & closing teeth together.8 days ago swelling began. Pt went to ER and was given zithromax, ibuprofen & tylenol #3.7 days ago swelling increased under tongue and into face.5 days ago, pt returned to ER where they did a CT scan and found nothing. Pt reports numbness in lip. Pt admitted to hospital and given IV clindamycin. MRI done and "something was found in lower left jaw". Pt started 300mg clindamycin.Today, patient referred from oral surgery for endodontic consult/vitality testing. Here's how he looked.

A small crack noted on the distal marginal ridge of #18. Thermal testing once again indicates a vital pulp. Typically, we would expect a necrotic tooth to be the source of the submandibular swelling that this patient has experienced.

Since tooth #18 is responding normally to thermal testing, we decided to take a CBCT to look for more evidence of the source of infection.

This coronal slice (.25mm) shows radiolucency around the distal root #18. This image is more conclusive than the standard 2D image.

A sagittal slice through the distal root of #18 shows the lesion and its perforation of the lingual plate.

An axial view of the distal root of #18 also shows perforation to the lingual.

These CBCT slices are conclusive enough to revise the pulpal diagnosis to "partially necrotic" and recommend endodontic treatment. It appears that the distal root is necrotic and the infection is spreading through the lingual plate.

RCT initiated. Upon access, we find vital pulp tissue in the mesial canals, and necrotic pulp tissue in the distal canal.

Further removal of the distal crack finds the crack extending down the distal root, below the CEJ. Extraction is recommended.

In endodontic diagnostics, we typically classify pulpal status as:

1. Normal2. Reversibly Inflammed3. Irreversibly Inflammed4. Necrotic

However, things are not always a cut an dry as that. This case illustrates that "partially necrotic" pulp is a possible classification of pulpal status.

15 comments:

I am a dental assistant at Summerlea Dental in Edmonton, AB. I thought this case was very similar to some of the ones that we are presented with. I have to agree with you that CBCT does play an important role in Endodontics. Great Article!

Thanks for sharing this interesting case. Pulpal diagnosis can be complex with not all signs and symptoms "adding up" to a clear diagnosis. I think the use of CBCT is also complex and there are costs to the procedures which have to be weighed against the benefits. As there are no guidelines for dentists it is really up to each practitioner how they will use this technology. In this case the CBCT clearly gave us more anatomical information than the PA. However, was that information necessary to get to the diagnosis that would ultimately dictate treatment? I didn't see a mention of the periapical diagnosis in the write up. Usually a cracked tooth with periapical pathology would exhibit pain on biting which could be reproduced with a bite test or percussion. Assuming this were the case, I would feel confident with moving forward with treating #18 given the following evidence:1. periapical symptoms2. periapical radiolucency evident on the distal root in PA3. crack visible on distal ridgeThe vital pulp would give me pause but in my mind there would be enough evidence pointing to #18 to move forward with treatment. The diagnosis would be asymptomatic irreversible pulpitis with symptomatic apical periodontitis. Ultimately the CBCT really was of no benefit in this case other than having some great images for documenting an interesting case. Unfortunately the cost to the patient, both financial and the extra exposure to radiation, are not worth the benefit of the scan. This is a great example of why we need good clinical studies so we can know when we really need to go the extra step with expensive imaging.

Thank you for your thoughtful comment. I appreciate your point of view.

In the case presented, there was no percussion sensitivity, normal response to cold, normal probings. The diagnosis at that point was: normal pulp & periapex with crack on disto-marginal ridge. The CBCT allowed me to change the pulpal diagnosis to "partially necrotic" and begin treatment without a clinical "guess".

How many times a day do you find yourself telling a patient, "We'll have to open it up and see..." whether that's resorption, decay, cracks, iatrogenic damage, perio defects, sinus involvement etc. I have found that CBCT gives us more information with which to make treatment decisions.

There is additional cost for this improved imaging, but we have kept that reasonable for our patients.

The additional radiation exposure is an important point, however the J. Morita Veraviewepocs 3De is the lowest radiation exposure on the market. It is the equivalant of about 4 periapical films. That is the equivalant of about 4 days worth of normal environmental background radiation exposure.

In this particular case, this patient had already had CT scan (which is a much larger radiation exposure), MRI and been admitted to the hospital. The cost and radiation associated with this lack of appropriate diagnosis cost him much more than the treatment recieved in our office.

I have been asked several times why CBCT would be used in endodontics.I am finding that a small field of view, low radiation CBCT (such as J. Morita Veraviewepocs 3De) has many applications.

As you can tell, I am very excited about this new technology and am confident it will become as important of a tool as the microscope is in endodontics.

In our practice we continue to use our best judgement to apply this technology as needed for the benefit of our patients.

Thank you again for your comments. I hope you will help us continue these discussions.

As an endodontist, I appreciate your thorough and thoughtful approach to this treatment. I take the same approach to fractured teeth and would have also recommended extraction as the most prudent choice.

The CBCT is an interesting tool but one that I have not yet adapted to using. My treatment would have been the same as yours based on almost as convincing RL on the D on the PA image. Strangely, the CBCT looks like it shows a RL on the mesial root as well. Seeing the lesion perforate the cortical plate is definitely cool though.

Between shift shots and traditional film radiographs, I can really get an excellent idea of tooth anatomy and periapical pathology. The CBCT adds something for sure, I am just not sure how much. The case that the salesman always show me are fractured roots (that are obviously fractured on PA) and this case again demonstrates that most cracks are not picked up on CBCT. The other one they always show is the missed ML on maxillary molars or DB on lowar molars (or mid mesial for that matter). I don't need a CBCT to tell me that an molars have 4+ canals; I end up retreating them day in day out, many missed by endodontists more experienced than I. The microscope, some patience, and a cup of six files gets the job done.

I will continue to consider it as an addition to my practice and will check back for more cases. Thank you for your efforts.

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The clinical information provided in The Endo Blog is designed to support healthy discussion regarding treatment choices, techniques, current research, current materials etc. among dental professionals and others interested in clinical endodontics.

The Endo Blog respects the confidentiality of individual patients. The clinical information presented in The Endo Blog will protect the identity of individual patients. Any cases that contain identifying photographs of a patient will be done with the patient's written consent.